1. Field of the Invention
The present invention relates to a keyless entry device including a car-mounted transmitter-receiver and a portable transmitter-receiver, and in particular, it relates to a key entry device in which one portable transmitter-receiver can be used only for one car-mounted transmitter-receiver even when one portable transmitter-receiver ID is registered for two car-mounted transmitter-receivers in a car manufacturing process.
2. Description of the Related Art
Vehicles such as cars generally have locks for doors to prevent theft or intrusion and breakage when not used. Doors have been locked or unlocked by inserting a key for starting an engine into a keyhole. However, so-called active keyless entry devices have come into use for convenience in which doors are locked or unlocked by operating the switch of a portable transmitter-receiver without inserting a key into a keyhole. Furthermore, so-called passive keyless entry devices have come into use in recent years in which doors can be locked or unlocked automatically without operating the switch but with a specified portable transmitter-receiver and in position. The passive keyless entry devices are generally given the function of the active keyless entry devices, or the function of the active entry, and some devices are given an electrical identifying function for engine startup to prevent the engine from starting until identification is made between a car and a portable transmitter-receiver, thereby increasing security.
This type of passive keyless entry devices having the function of the active keyless entry devices include an active keyless entry device in which an operation switch is disposed on the portable transmitter-receiver, wherein when a user operates the operation switch of the portable transmitter-receiver, the portable transmitter-receiver generates an instruction signal corresponding to the operation mode and transmits the generated instruction signal to a car-mounted transmitter-receiver by radio, and a passive keyless entry device in which the car-mounted transmitter-receiver generates a low-frequency signal including a wakeup signal and a data signal at regular intervals, transmits the generated low-frequency signal to the portable transmitter-receiver by radio, wherein when the portable transmitter-receiver has received the low-frequency signal, the portable transmitter-receiver generates a radio-frequency signal including an instruction signal and transmits the generated radio-frequency signal by radio (for example, refer to Japanese Unexamined Patent Application Publication No. 2000-320212).
In this case, the active keyless entry devices transmit an instruction signal to the car-mounted transmitter-receiver by radio by the user operating the operation switch of the portable transmitter-receiver and as such, devices disposed in the vehicle cannot be operated unless the user etc. operates the operation switch of the portable transmitter-receiver, so that the door-locked state of the vehicle does not change to an unlock state by mistake.
On the other hand, for the passive keyless entry devices, radio signals are transmitted or received between the portable transmitter-receiver and the car-mounted transmitter-receiver without operating the operation switch of the portable transmitter-receiver to allow automatic operation of the devices disposed in the vehicle, thus having higher functionality than that of the active keyless entry devices.
In such keyless entry devices, the ID of the portable transmitter-receiver is registered in the car-mounted transmitter-receiver so as to bring the car-mounted transmitter-receivers mounted on a vehicle into correspondence with a portable transmitter-receiver used therefor. In this case, a portable transmitter-receiver in which an ID unique to the portable transmitter-receiver is written to its ROM is first prepared. In registration of the ID of the portable transmitter-receiver to the car-mounted transmitter-receiver, the car-mounted transmitter-receiver is set in a registration mode in which the ID of the portable transmitter-receiver is registered, and then a switch disposed on the portable transmitter-receiver is operated, as in the active entry mode, to transmit a signal containing the ID from the portable transmitter-receiver. When the car-mounted transmitter-receiver has received the signal, the ID of the portable transmitter-receiver contained in the signal is written to an RAM provided in the car-mounted transmitter-receiver. Then a signal containing the ID of the portable transmitter-receiver and an instruction is transmitted by switch operation to identify the ID of the portable transmitter-receiver, which is registered in the car-mounted transmitter-receiver, wherein when identification has been made, the door is locked or unlocked according to the specified instruction signal. While the registration of the ID of the portable transmitter-receiver is generally made by vehicle manufacturers during a vehicle manufacturing process, it is sometimes made by vehicle dealers or rarely by a user who bought the vehicle, for example, when the portable transmitter-receiver was lost or when an additional portable transmitter-receiver is used.
Since the registration of the ID of the portable transmitter-receiver to the car-mounted transmitter-receiver is made to specify a portable transmitter-receiver used for the car-mounted transmitter-receiver as described above, duplicate registration of the ID of one portable transmitter-receiver to two or more car-mounted transmitter-receivers is not generally intended. However, for registration of the ID by a vehicle dealer, when the car-mounted transmitter-receivers of multiple vehicles are set in a portable transmitter-receiver registration mode, the ID of one portable transmitter-receiver will be registered in the car-mounted transmitter-receivers of the multiple vehicles at the transmission by the portable transmitter-receiver.
When the ID of one portable transmitter-receiver is registered in two or more car-mounted transmitter-receivers, two or more car-mounted transmitter-receivers can be controlled in normal service condition by using one portable transmitter-receiver, or in other words, the door lock of vehicles that mount the car-mounted transmitter-receivers can freely be controlled, which is not desirable for the purpose of keyless entry devices.
With another structure in which the ID of the car-mounted transmitter-receiver is written manually to individual portable transmitter-receiver using an additional writing device, and a signal containing the IDs of the portable transmitter-receiver and the car-mounted transmitter-receiver is sent at the transmission of a request signal by a passive entry, wherein when the IDs agree with each other in the portable transmitter-receiver, an answer signal is generated to unlock the door, the ID of the car-mounted transmitter-receiver is different from that, so that no identification is made to prevent unlock. On the other hand, for active entry, the identification is made only with the ID of the portable transmitter-receiver to allow door lock, thus posing the problem of difficulty in determining whether the malfunction is caused by failure or misregistration of the ID, because many vehicle dealers do not generally know the details of identification method.